Orthographic game but want a single object to be drawn in perspective (SOLVED)

Questions
#1

I have a 2d, orthographic game, but I would like to have an object hovering over/in-front of the game, that is drawn in perspective. The object rotates along the y-axis. I don’t think a special, perspective camera can affect a single game object, but perhaps I could write a shader to draw the pixels in perspective based on the z-value of the pixels.

I’m hoping for a straight-forward solution. Suggestions?

#2

You need to assign a material with a different tag so that you can call render.draw() an extra time in your render script. Before you call render.draw() you also need to set a perspective view projection using API reference (vmath)

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#3

I don’t know the render system, but I’ll try to figure it out. I’m pretty sure your suggestion will lead me to the right solution. Thanks.

#4

Thanks! Looks like it’s working.
I made a material with the tag “spinObj”. and assigned it to the sprite in the object I wanted drawn in perspective.
Here’s what I added to a copy of the default renderer.

--
-- projection that draws in perspective
--
local function persp_projection(near, far)
    return vmath.matrix4_perspective(3.141592/6, 2, near, far)
end

-------- added this within init function
    self.spinObj_pred = render.predicate({"spinObj"})

-------- added this within the update function.
    -- draw spinning object in perspective
    --
    local oView = vmath.matrix4_look_at(vmath.vector3(0, 0, -900), vmath.vector3(0, 0, 0), vmath.vector3(0, 1, 0))
    render.set_view(oView)
    proj = persp_projection(self.near, self.far+200)
    render.set_projection(proj)
    render.draw(self.spinObj_pred, {frustum = proj * oView})
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